Patent GB-845196-A (GB)
Title: Improvements in or relating to centrifugal clutches
IPC: F16D43/09
Filed: 1956-09-13
Abstract: 845,196. Friction clutches. FRANCAISE DU FERODO S.A. Sept. 13, 1956 [Sept. 17, 1955; Oct. 15, 1955; Nov. 26, 1955], No. 28058/56. Class 80 (2). In a motor-vehicle centrifugal clutch of the floating mass-carrier type, wherein a presserplate 13 is actuated to engage a main clutch disc 14 through springs 15, transfer plate 16, thrust bearing 17 and cam-plate 18, by centrifugal masses 19, pivoted on a floating carrier 20, which, for clutch release is held by an electromagnetic clutch - brake 25, de - energization of which permits a blade spring mounting 24 to move the armature 23 into friction clutch engagement with an input shell 22 for driving the mass-carrier 20 to cause engagement of the main clutch, means are provided for modifying the torque which drives the mass-carrier 20, suchmeans being controlled automatically responsive to speed or time, or manually in response to a manual control, such as the engine accelerator pedal, provided primarily for some other purpose. At low engagement speeds, the mass-carrier drive-torque is reduced to produce a longer slip interval, so that during gear shift, when a yielding gear-shift lever 27, e.g. as described in Specification 751,785, energizes the brake winding 25 for coincidental clutch release, subsequent clutch re-engagement is rendered more gradual if the shift is being made at low speed. In Fig. 1, this torque modification is by a clutch shoe 28 carried on a tangential blade spring on the input shell 22 and moved centrifugally into frictional engagement with the mass-carrier 20 to increase the drive torque thereon at higher speeds. In Fig. 3 (not shown), the shoe 28 and coacting surface are arranged outside the input shell, and in Fig. 4 (not shown), the shoe is positively retracted from the mass-carrier 20 by an additional magnet winding in parallel with the mainclutch release winding 25. In Figs. 5 and 6, (not shown), the shoe 28 is carried by the masscarrier 20 and frictionally engages the shell 22. In Figs. 7 and 8 (not shown), there is an outer shoe in addition to the shoe 28, centrifugally released at normal speeds, but allowed to engage and drive the mass-carrier ineffectively at idle speeds to ensure a more rapid acceleration of the mass-carrier when its clutch 23 is engaged and engine speed increased. In Fig. 9 (not shown), the bearings 17 and 21 are both replaced by plain collars of graphite or sintered material, which apply a permanent friction torque to the mass-carrier 20 and cam 18 and are subjected to axial pressure by the masses themselves, so that their torque contribution increases with speed. In Figs. 11 and 12 the clutch itself is unmodified, torque modification being produced by the external control. When operation of the gear-shift lever 27 energizes the main clutch release winding 25 through a relay 44, it also energizes a time-relay 64 which deenergizes a solenoid 59 to release a plunger 58 for upward movement by a blade-spring 60. This, through levers 55, 52, applies a brakeshoe 51 to the armature 23 which is secured to the mass carrier 20, Fig. 1. The drive-torque acting on the mass-carrier during engagement is thus reduced unless the accelerator pedal P is depressed to reduce brake shoe pressure. When the relay circuits are broken by release of the gear-shift lever 27, the relay 64, after a time delay, permits re-energization of the solenoid 59 to release the brake shoe. In Fig. 10 (not shown), the clutch-release winding 25 is supplied during engagement with a lightenergizing current in the normally de-energized clutch-engaged position, to reduce mass-carrier drive-torque, through a circuit completed by release of a clutch-engaging relay, such circuit including a variable resistor controlled by the accelerator pedal or engine speed, and a release switch controlled by the accelerator pedal, centrifugally, or by time switch. Specification 845,197 also is referred to. Reference has been directed by the Comptroller to Specification 586,910.